Khaufpur, the city in which your novel is set, is a thinly disguised representation of the Indian city of Bhopal, which suffered one of the world's worst industrial disasters in 1984 when a pesticide plant released over 40 tonnes of poisonous gas. Did you write Animal's People in order to help the world remember its victims?

"You think books should change things," the Kakadu jarnalis tells Animal. "So do I. When you speak, talk straight to the people who'll read your words. If you tell the truth from the heart, they will listen."

Personally, I don't insist that writers have a duty to change things. Animal does because he's a Khaufpuri. What I look for in a novel are compelling characters and a tale well told. If it can also be a power for good in the world, so much the better.

I hope Animal's People will help the Bhopalis' long struggle for justice, but trying to teach Bhopal studies via a novel would kill the fiction.

People assume Animal's People must be a grim read, but New York magazine called it "scabrously funny", which delights me. In the end, the only way to deal with tragedy is to laugh at it.

Some readers have found Animal's voice disconcerting. Was it intentional to make readers feel a little uncomfortable around him sometimes?

Animal is sick of books about Khaufpur that achieve nothing. He's angry and cynical. He goads, provokes. As you read him, he's reading you.

I wanted Animal to be familiar yet disturbing. One translator assumed that the relentless use of the present perfect - "I've gone up the tree" - was an Indianism, but it's English football-speak. At the same time Animal's talk is spiced with argot and inversions - "Khaamush. Silent then, I'm" - that sound bizarre but are direct lifts from Hindi, whose word order can be almost randomly shuffled.

If you hate foul language, blame Animal not me. At the Edinburgh Festival I apologised for Animal's constant use of the word that the dramatist Fletcher described as "sunt with a C, which is abominable". After the reading someone came up to me and said, "This is the 21st century. I think you're more shocked than we are."

The novel is dedicated to Sunil Kumar. Do you draw from some of his life experiences in Animal's People?

Animal inherits from Sunil his sense of humour, blunt speech and delight in shocking the unwary. Both lived on four rupees (5p) a day. Sunil went everywhere on foot and accused me of being an "auto-riding superstar" just as Animal accuses Elli doctress in the novel.

In 2004, I taped a very long interview with Sunil. The batteries ran low and, when played back, most of the tape was squeaky laughter. Sunil could be very funny, but his life was anything but.

Sunil's parents and three of his five siblings were killed on that night. He woke among corpses en route to a pyre. Aged 12, he worked 18-hour days to provide for his younger brother and sister. He was kind to other children, helped form an organisation of orphans and threw himself into the survivors' struggle for justice, becoming one of its best-loved characters.

As the years passed Sunil began having bouts of schizophrenia. He'd describe these as his mad times. He hallucinated and heard voices. He believed people were coming to kill him and once ran away into the jungle to live like an animal.

Some think that Animal's People strays into magical realism. I doubt if there's much magic in madness, but Animal is his own kind of realist. When people tell him his voices are imaginary and urge him to turn to religion, he replies, "To deny what you do see and hear, and believe in what you don't, that you could call crazy." This too, he learned from Sunil.

Sunil's death, last July, was reported all over the world. On behalf of his friends I wrote a tribute. It ended thus:

Sunil brother, you thought you were mad, but a world without justice is madder. At least you are now safe. We scattered your ashes in the flooded Narmada river, and for your funeral feast followed your precise instructions: a quarter bottle of Goa brand whisky, mutton curry from Dulare's hotel near the bus stand, betel nut, tobacco and all. Were you there with us? If not, who was it that in the darkness chuckled, "I am no longer afraid of being killed - I am already dead and fearless"?